1. Field of the Invention
The present invention relates to a copying apparatus provided with a control device for controlling the lens position for varying the image magnification ratio.
2. Description of the Prior Art
In conventional copying apparatus capable of varying the image magnification or power ratio, the copying lens is usually moved by a motor to a position corresponding to a desired lens power, while a lens position detector is used for identifying whether the lens is actually in such desired position, thus controlling the position of the lens. Such conventional copying apparatus with such variable image power function is usually capable of image reduction in two image powers, for example 0.68 and 0.78 times of the original size, and a lens position detector is provided for each lens position corresponding to each image power. However in a copying apparatus capable of providing multiple image powers, such method, requiring lens position detectors corresponding to the number of available image powers, is disadvantageous not only in the functional reliability but also in the cost of the apparatus. Also the mechanism for providing multiple image powers is inevitably quite complicated and does not practically allow the detection of lens position.